Hinako Shibuno's lead at the U.S. Women's Open was cut to one shot after she battled to a three-over 74 in the third round on Saturday.
The 22-year-old from Japan, who won the Women's British Open last year, mixed four bogeys with one birdie on the Champions Golf Course Cypress Creek in Houston, Texas.
After holding a three-stroke lead at the halfway mark, Shibuno will carry a one-shot advantage into the final round.
Amy Olson, the first-round leader, carded an even-par 71 to be at three under, while Ji Yeong Kim2 surged into contention.
Kim was one of just two players to manage an under-par third round, shooting a 67 to climb into one under, sitting alongside Moriya Jutanugarn (72) in a tie for third.
While making four birdies, Kim hit 10 of 14 fairways and needed just 23 putts in the third round.
Lydia Ko continued her consistent showing with a 72 that sees her at even par alongside Yealimi Noh (72), Megan Khang (74) and amateur Kaitlyn Papp (74).